The process in accordance with the present invention can be used to condition oxide ore or concentrates containing substantial amounts of carbonaceous matter which can also contain sulfides such as iron sulfide. However, in order to facilitate the description of the present invention, the invention will be described in terms of treatment of tungsten concentrates, particularly scheelite concentrates.
Frequently, organic matter is associated with oxide concentrates. The concentrate can contain substantial amount of flotation reagents in addition to sulfides, such as pyrrhotite, pyrite or chalcopyrite. Natural organic matter, such as humus can also be present. The presence of organic matter, particularly flotation reagents, can interfere with subsequent hydrometallurgical processing. For example, the presence of flotation reagents can cause substantial foaming during hydrometallurgical processing. Foaming can lower the capacity of the processing vessels, or can cause hazardous conditions by overflowing such vessels. If the flotation reagents are carried on to subsequent process steps, such as solvent extraction, the flotation reagents can contaminate the organic phase causing substantial processing inefficiencies and often requiring periodic replacement of the organic extractant. In the processing of tungsten concentrates which contain significant amounts of molybdenum the presence of flotation reagents or other organic matter can reduce the effectiveness of the molybdenum removal operation. The presence of sulfides can create unpleasant or unsafe working conditions if during a subsequent process hydrogen sulfide is evolved.